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February 19, 2010

P2P Sharing and Reasonable Expectation of Privacy

Having a reasonable expectation of privacy is the basis for the application of the 4th amendment of the US Constitution which provides protection against illegal searches and seizures. If you have a reasonable expectation of privacy in the items to be searched the police must get a warrant before any search. Of course, there are some exceptions to this rule (exigent circumstances, search incident to arrest, etc.)... but let's talk about a computer.

Do we have a reasonable expectation of privacy in the contents of our hard drives? It depends on what software you are running. The law says that if you run a peer to peer, you impliedly accept that people can access the contents of your files. Therefore, you do not have a reasonable expectation of privacy. As a consequence, if the police find evidence of illegality, such evidence can be used to prosecute you.

This is what case law says about file-sharing and this principle was recently reaffirmed in a child-pornography case.

The defense attorneys in this case tried to distinguish the facts arguing the complexity of the tools used by the police to access the computer of the suspect and his subjective mental state. Of course, the subjective mental state is irrelevant and the argument of "system penetration" (AKA hacking) was trumped by the circumstance that the data was otherwise accessible through a "widespread" exposition to the public. In fact, there was not any system penetration and the government only used a hash-mark analysis as a sorting mechanism to prevent the government from having to sift, one by one, through suspect's already publicly exposed files.

However, this case is important in clarifying at least one principle.
What if you are using a sharing software that you think is not publicly accessible? If the functioning of the software implies exchange of communication, you are advised of your reduced expectation of privacy.